Submersible salvage unit and method of operation

ABSTRACT

A submersible salvage unit is provided with a support frame which carries opposed pairs of downwardly depending arms for grasping a sunken vessel or other object. The arms can be actuated from grasping to inoperative positions by relative vertical movements of pontoons which are also carried by the support frame of the unit. The relative movements are effected by movement of either the pontoons or the support frame relative to the other. Buoyancy compensators are provided in the salvage unit to adjust buoyancies to match loads which are to be lifted, and the buoyancy compensators include means for rapidly releasing buoyancy gas from the pontoons, if necessary. Also, buoyancy compensators on opposite sides of the salvage unit may include stabilizers which relate the compensators to each other in their operations to maintain stable attitudes of the salvage unit when it is lifting a load. A method of operation provides for an alignment and sinking of the salvage unit over a sunken vessel, and engagement of the vessel is accomplished by adjusting buoyancies of the entire salvage unit.

United States Patent 1191 Kriedt et al. 1 1 May 15, 1973 [54] SUBMERSIBLE SALVAGE UNIT AND 3,537,412 11 1970 Henderson ..114 0.5 D

METHOD OF OPERATION [76] Inventors: Frederick A. Kriedt, 1722 East gummy z g g g g West l-lwy., Silver Spring, Md.; tmmey Us ar y us am Thomas H. Sundstrom, 7706 Nicollet Avenue S., Bloomington, Minn.; [57] ABSTRACT Richard W lk), 15913 M ti A submersible salvage unit is provided with a support Road, Roseville, Mich. frame which carries opposed pairs of downwardly depending arms for grasping a sunken vessel or other ob- [22] Flled' 1970 ject. The arms can be actuated from grasping to in- [21] A L N 67,263 operative positions by relative vertical movements of pontoons which are also carried by the support frame Relat d U Applicati n a of the unit. The relative movements are effected by [62] Division of set No 765,897 Oct. 8, 1968' movement of either the pontoons or the support frame relat1ve to the other. Buoyancy compensators are provided in the salvage unit to adjust buoyancies to match IN/16:63:33; loads which are to be lifted, and the y y pensators include means for rapidly releasing buoyan [58] Fleld of Search y g from the pontoons if necessary Also y cy compensators on opposite sides of the salvage unit 6 R f may include stabilizers which relate the compensators [5 1 e erences Cited to each other in their operations to maintain stable at- UNITED STATES PATENTS titudes of the salvage unit when it is lifting a load. A method of operation provides for an alignment and 3,335,685 8/1967 Gimbel ..114/16 E sinking of the salvage unit over a sunken vessel, and 3,512,493 1970 Hananger -114/53 engagement of the vessel is accomplished by adjusting 1,201,051 10/1916 Jack ..1 14/05 T buoyancies of the entire salvage unit 2,889,795 6/1959 Parks ..ll4/0.5 D

9 Claims, 19 Drawing Figures PATENTEUHAYI 51915 3. 732 ,838

SHEET 2 [1F 6 ATTORNEYS PATEMEDHAHSIQYS 3 732,838

SHEET 5 OF 6 m; urn l/JX////////////// l CKl/Y W INVENTORS ATTORNHZS SUBMERSIBLE SALVAGE UNIT AND METHOD OF OPERATION This is a division of application Ser. No. 765,897 filed Oct. 8, 1968.

BACKGROUND AND BRIEF DESCRIPTION OF INVENTION This invention relates to the art of salvaging sunken vessels, or other objects, from a body of water, and in particular, the invention is concerned with improvements in salvaging units and methods of operation for retrieving sunken vessels from deep water.

It is known in the prior art to provide for various structures and devices which function to assist in the salvage of sunken vessels. Prior art arrangements have provided for an attachment of buoyancy tanks to sunken vessels, and various attempts have been made to design salvage rigs which can embrace and lift a sunken object. For example, Buell U.S. Pat. No. 1,616,410 and Powell U.S. Pat. No. 1,691,738 each describe designs for rigs which are intended to be lowered into engagement with a sunken vessel for grasping and lifting the same. In the Buell arrangement, grasping arms are actuated by a number of lines which must be manipulated from the surface, and Powell discloses a design for actuating grasping arms by adjusting the buoyancy of tanks which are rigidly connected to the grasping arms. Other known prior art on this subject includes U. S. Pat. Nos. 1,415,533; 1,807,361; 1,854,026; 1,851,892; and 2,280,547.

Although various designs and assemblies have been attempted in the past, it has been our experience that prior designs and assemblies have not solved the special problems of salvaging relatively large sunken vessels from deep water. It can be appreciated that the grasping and floating of a sunken vessel can be quite dangerous, and extremely unstable conditions can arise while the vessel is being lifted from its sunken position to the surface of a body of water. Actual salvaging operations in the past have involved substantial dangers to all personnel involved, and much effort can be lost and wasted if a vessel is lost from a salvaging rig during the floating or surfacing operations. Accordingly, the present invention is concerned with problems of a safe and controlled handling of relatively large objects which must be received and lifted to the surface of a body of water by a submersible salvage unit. The improvements of the present invention provide for greater safety and control of the entire operation so that sunken vessels can be retrieved relatively safely and at costs which are acceptable to present day requirements.

The salvaging unit of the present invention is of the type which can be floated to the location of a sunken vessel so as to be sunk over the vessel for grasping the same and lifting it to the surface ofa body of water. The salvage unit includes a support frame means which has sufficient length and width to position two rows of grasping arms over and around a vessel which is to be lifted. The support frame means provides rigidity and strength to the entire salvage unit, and buoyancy tanks are included in the structure of the support frame means for assisting in an adjustment of buoyancy conditions for receiving, releasing and handling a load. A plurality of grasping arms are carried within the support frame means so as to define two rows of downwardly depending arm members having inwardly projecting end portions at their lowermost ends. The arm members are connected to the support frames so as to be actuatable from an inoperative position where the two rows of arms are spread away from each other to an operative, grasping position where the two rows of arms are moved towards each other and towards a central space defined within the confines of the salvage unit. Thus, opposed arms can be moved away from each other for placing the salvage unit over a sunken vessel, and then, the arms can be moved towards each other to grasp and retain the vessel for a subsequent floating of the combined unit and vessel to the surface of a body of water. The present invention provides for a unique actuation of the grasping arms by means of pontoons which are carefully controlled in their relationship to the operation of the grasping arms. Pontoon means, which may be in the form of a plurality of pontoons positioned along each side of the salvage unit, can be lifted and lowered on track structures associated with downwardly depending leg members of the salvage unit support frame. Lifting and lowering movements of the pontoons function to actuate the positions of the grasping arms, and the pontoons are linked to the grasping arms so as to transmit the controlled movements of the pontoons to desired movements of the grasping arms. A pontoon means on one side of the salvage unit controls grasping arms on an opposite side of the unit so that maximum leverage is obtained in the inward movements of the grasping arms towards the side walls of a vessel which is to be received and retained by the arms. In addition to providing for a controlled movement of the pontoon means along tracks associated with the support frame structure, there is provided a linkage connection between the pontoons and the grasping arms which permits movement of the pontoons relative to the support frame structure without affecting the positions of the grasping arms. This arrangement is important because it permits an adjustment of draft of the entire salvage unit and a retained vessel once it has reached the surface without any danget of losing the vessel.

The invention also provides for novel buoyancy compensator devices associated with the pontoons, or other buoyancy tanks, which permit a careful regulation of buoyancy conditions for the entire salvage unit. The buoyancy compensators comprise tubular members which provide a communication between a sealed interior of the pontoons, or of separate compartments within a given pontoon, with an outside environment (the sea) so that controlled amounts of water can be admitted into pontoons to adjust buoyancy. Means are provided for adjusting the distance at which the lowermost end of each buoyancy compensator extends into the interior space of a pontoon, and the tubular members of the compensators may include telescoping sections to permit such an adjustment. Also, means are provided for rapidlyventing buoyancy gas from the pontoons with the buoyancy compensators so that extremely unstable attitudes can be avoided during a salvaging operation. Finally, a novel arrangement is provided by stabilizer valving means associated with the buoyancy compensators to balance opposed pontoons on opposite sides of the salvage unit.

The method of operation provided by the present invention includes steps of aligning a salvage unit with a sunken vessel and sinking the unit into an embracing position over the sunken vessel after adjusting positive buoyancy capabilities of the salvage unit to substantially match the calculated, or known, weight of the sunken vessel. In the context of the present invention, the capabilities of the pontoons are adjusted and set by the novel arrangement of compensators associated with the pontoons, and a careful matching of buoyancy of all pontoons with the weight of a sunken vessel permits a controlled lifting of the combined weights of the salvage unit and the vessel by adjusting positive buoyancy of additional buoyancy tanks associated with a support frame structure of such a unit.

The salvage unit of the present invention permits a safe and controlled handling of sunken vessels without unreasonable or uneconomical requirements for additional devices or impossible control functions to be carried on by surface support personnel. These and other features and advantages of the present invention will become apparent in the more detailed discussion which follows, and in that discussion, reference will be made to accompanying drawings as described below.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an elevational schematic view of the salvage unit of this invention being floated into an aligned position with a sunken vessel;

FIG. 2 is an end elevational view of the salvage unit, showing its grasping arms in outwardly extended positions for receiving a sunken vessel;

FIG. 3 is an end elevational view, similar to FIG. 2 showing the grasping arms in closed positions for retaining and lifting a sunken vessel;

FIG. 4 is a top plan view of the salvage unit;

FIG. 5 is a partial perspective view, schematically illustrating relationships of elements in the salvage unit assembly;

FIG. 6 is a top plan view of a pontoon means associated with one side of the salvage unit;

FIG. 7 is a detailed elevational view of a single grasping arm means associated with the salvage unit;

FIG. 8 is a detailed elevational view, partially in cross section, of a jetting device associated with the arm means of the unit;

FIG. 9 is an end elevational view of a leg member associated with the support frame structure of the unit;

FIG. 10 is a detailed elevational view of a buoyancy compensator associated with the pontoon means, partially in cross section;

FIG. 11 is a cross sectional view taken at lines 11 ll of the buoyancy compensator of FIG. 10;

FIG. 12 is a top plan view of structure associated with a stabilizer valve means carried at a lowermost end of the buoyancy compensator of FIG. 10;

FIG. 13 is a detailed top plan view of a valve means of the type shown in FIG. 12;

FIG. 14 is a schematic view illustrating the relationship between opposed buoyancy compensators, and their associated stabilizer valve means, for maintaining a balance between opposite sides of the salvage unit;

FIG. 15 is a schematic elevational view of a flexible pad means associated with the arm means, for engaging and holding a sunken vessel in place relative to the arm means;

FIG. 16 is a view similar to FIG. 15, showing a variation in the arrangement of FIG. 15;

FIG. 17 is an elevational side view of the flexible pad means illustrated in FIG. 16;

FIG. 18 is a top plan view of a piping diagram for the salvage unit, showing a plan for controlling admission of air to various parts of the unit; and

FIG. 19 is a view of a guiding system associated with the salvage unit for aligning the unit with buoys marking a sunken vessel or object.

DETAILED DESCRIPTION OF INVENTION FIG. 1 illustrates the salvage unit of the present invention in its environment of intended use. The salvage unit comprises a complete rig which can be floated and towed to the location of a sunken vessel, and then, the unit can be aligned and sunk into a position over the vessel for receiving and retaining the vessel within opposed grasping arms associated with the unit. The salvage unit can be of any size and configuration, but it should be of sufficient dimensions to fully embrace and include whatever sunken vessel, or other object, is to be received within the grasp of its opposed arms. The particular constructional features and relationships which are offered by the present invention permit the use of such a very large salvage unit in operations which are controlled, safe and economical for many present day salvaging requirements. Also, the provisions of this invention for careful control and balancing of buoyancy factors of the salvage unit permit the unit to be safely used in deep water operations where special problems of pressure, floatation, and remote control arise. The operation and use of the salvage unit, as depicted in FIG. 1, will be discussed in greater detail later.

FIGS. 2 through 6 show elevational and plan views of the unit and of components making up the salvage unit of the present invention. The salvage unit includes a support frame structure 10 which functions to provide strength and support to the entire unit and to components which are a working part of the unit. It is important that a salvage unit, of the size contemplated by this invention, maintain its integrity while being floated and towed as well as during actual salvage operations; and the structural relationships offered by this invention provide for a strong unit that has a capability of embracing a complete vessel and all its superstructure and which will hold together while being operated at sea. The support frame means 10 has an upper level structure 12 which is constructed in the form of compartmented tanks (as shown in FIG. 4) for providing a certain amount of buoyancy control to the entire unit, and it can be seen that the upper tank structures 12 are of a configuration to receive a plurality of opposed arm means 14 which are connected to portions of the support frame structure for movement relative thereto. As shown in FIG. 4, the plurality of arm means 14 may comprise several sets of opposed pairs of arms which extend laterally outwardly from pivotal mounting connections 16 on the support frame structure. Other mounting arrangements may be used for permitting movement of the arm means relative to the remainder of the salvage unit, but pivotal mounting means 16 are provided in the illustrated embodiment. The pivotal mounting means 16 may comprise any known mounting pin carried by each arm means 14 and received into reinforced structure associated with the upper level structure of the support frame 10. As illustrated in FIG. 4, the pivotal mounting points of opposed arm means, of each pair of arms, are offset from one another so as to provide a preferred alignment of lower portions of the individual arms with side wall portions of a sunken vessel. Also, offset pivotal connections provide for a stronger mounting of all arms in the support frame structure of the unit. Thus, each arm has its own hinged mounting relative to the support frame, and this provides a stronger structure than would be possible with a single hinging means being common to more than one arm. Although the illustrated embodiment of FIG. 4 shows a use of four pairs ofopposed arms, it is to be understood that other numbers of arms may be utilized in any given structure.

The arm means 14 function as grasping arms for engaging and retaining a sunken vessel within the confines of a space defined between two rows of depending lower portions of such arms. Each arm has a general configuration as shown in FIG. 7, and each arm includes a downwardly depending portion 18, a lowermost projection for placement beneath a sunken vessel, and an upper level portion 22 which functions as a lever for rocking the entire arm about its pivotal connection at 16. Considering a single pair of opposed arms, it can be seen that the depending portions 18 of each arm extend downwardly on opposite sides of the salvage unit, and the upper portions 22 of the opposed arms extend past each other from opposite sides of the salvage unit so that each arm is actuated from a side of the unit which is opposite to the position of its depending portion 18. This arrangement provides for maximum leverage and for a better control of the rocking movements of individual arms about their pivotal connections 16. Furthermore, this arrangement provides for a positive control of arm movements by adjusting buoyancy conditions for the entire unit, and without a necessary requirement for collateral driving mechanisms. An end view of opposite pairs of arms having upper level portions 22 bypassing each other can be seen in FIGS. 2 and 3, and a top plan view of the same relationship is shown in FIG. 4. FIG. 5 illustrates a configuration for the upper support frame 10 so that opposed pairs of arms can be rocked about their pivotal connections to the compartmented tank structure of the upper support frame.

One of the difficulties in prior art designs for salvage units of the type which are intended to grasp and retain sunken vessels has been a lack of control in effecting actual movements of grasping arms, or other grappling devices, and this problem has been compounded by a lack of control in maintaining a stable attitude of a sunken vessel once it is received into a salvage rig. Furthermore, prior designs have not provided for an easy release of a vessel once the vessel is surfaced or if unstable conditions are encountered during a lifting operation. The present invention provides for improvements in controlling the movement of the grasping arms 14, discussed above, and in addition, a better control is provided for maintaining a stable and upright attitude of the combined salvage unit and a retained vessel once the vessel is being lifted towards the surface of a body of water. As shown in FIGS. 3 and 4 the outermost ends of the upper portions 22 of each arm means 14 are linked to pontoon means 24. The linking connection is indicated generally at 26, and, in one embodiment, the linkage may comprise a hydraulically actuated ram, of known construction, for effecting an adjustment of the length of the linkage between the pontoon means 24 and their associated grasping arms 22. Alternatively, the linking means 26 may comprise flexible or telescoping elements, and known jacking devices may be connected to the pontoon means 24 to provide movement of the pontoon means relative to the support frame 10. The pontoon means 24 may comprise one or more sealed tanks or pontoons (which may be compartmented) positioned on opposite sides of the salvage unit and carried on depending leg members 28 associated with the support frame structure 10. By carrying the pontoon means 24 on fixed structure associated with the support frame means 10, it is possible to obtain a carefully controlled and guided movement of the pontoon means 24 relative to the support frame 10 and relative to any sunken vessel retained within the confines of the salvage unit. FIG. 4 illustrates a top plan view of two pontoon means placed on opposite sides of the salvage unit, And each pontoon means is constructed as a compartmented tank which is sufficiently air tight between adjoining compartments to permit a control of buoyancy of each compartment of each pontoon means. Alternatively, separate pontoons can be associated with each of the arm means 14, but the preferred arrangement is shown in FIG. 4. FIG. 6 further illustrates the pontoon means 24 for one side only of a salvage unit. Each pontoon means 24 includes rigidly affixed support structures 30 for carrying the pontoon means 24 on a plurality of depending legs 28 associated with the support frame 10. Each structure 30 may be in the form of a sleeve or collar which completely encloses whatever cross sectional configuration is provided for a depending leg 28, and each leg 28 may be provided with tracks or rails for permitting a sliding engagement of the structure 30 therewith. Additional structures and devices, as are well known for jacking drilling platforms and other seagoing structures on columns, may be included to provide a smooth movement of each pontoon means 24 up and down a plurality of depending legs 28, and rollers or other bearing means may be used to obtain a smooth movement between the pontoon and the support frame.

When all of the structures which have been discussed so far are assembled, it can be seen that there is provided a relatively rigid support frame 10 having two parallel rows of depending legs 28. Pontoon means 24 are carried for sliding movements up and down the two parallel rows of depending legs 28, and the movements of the pontoon means 24 (or of the support frame relative to the pontoons) are transmitted-to corresponding movements of upper arm portions 22 which are linked to the pontoon means. Each upper arm portion 22 transmits its movements to a downwardly depending arm portion 18 by rocking the entire arm about its pivotal connection to the support frame 10, and this movement is used to effect an opening and closing of opposed rows of depending arms carried within the confines of the support frame 10. Thus, opposite rows of arm means 14 can be spread away from each other to receive a sunken vessel (or to discharge the same once it is floated), and the opposite rows of arms can be moved towards each other by adjusting the buoyancy of the pontoon means 24 or of the frame 10 so as to move the pontoon means relative to the support frame 10 from which they are carried.

FIG. 8 illustrates additional features and details of structures associated with the arm means 14. At the lowermost end of each arm means (or of selected arms ofa given unit), devices may be provided to assist in the insertion of the lowermost end 20 underneath a sunken vessel. Generally, the submersible salvage unit of this invention will operate in areas where the sea bottom is relatively soft, for example, as found on most of the Continental Shelf of the United States, but collateral devices may be used to assist in the insertion of the lower end of the arm means underneath a vessel. One such assistance device may be in the form of a jetting system for supplying a water jet through a conduit 32 so as to assist in the movement of the arm through mud or other soft bottom conditions. Also, the use of a water jet assists in eliminating a vacuum which usually is created by an initial lifting of a large vessel away from a soft bottom upon which it has been resting. In addition to a jetting system, there may also be provided vibrator devices 34 which may be in the form of eccentric fly wheels operated by remote control to set up a frequency of vibration at the lowermost ends of the arms 14. The jetting devices 32 and vibrators 34 may be used separately or in combination with one another, depending upon the bottom conditions encountered during a salvaging operation. Electric motors, hydrazine turbines, or other devices may be carried in the legs to operate pumping functions for the water jet system and vibrating functions for the vibrating systems.

FIG. 9 illustrates a detail of a depending leg member 28 connected to the upper structure 12 of the support frame means 10. Each leg member 28 is rigidly affixed to the support frame structure and is reinforced to support and carry a pontoon means 24 associated with a plurality of such leg members along one side of the support frame structure. In addition, each leg member may be provided with track elements 36 for receiving the structures 30 carried by the pontoon means 24. In the illustrated embodiment, four depending leg members are provided on each side of the support frame structure so as to define two parallel rows of legs which can receive and carry the two separate pontoon means 24 on each side of the salvage unit. The leg members 28 may be of a hollow construction so that they can contribute to additional buoyancy for the support frame, and each leg may include an interior space which communicates with at least one compartment of the upper support frame structure. Also, conventional jacking mechanisms may be included in the leg structures for jacking the pontoons up and down the legs. Such jacking devices are of a well-known construction and are typically used for offshore drilling platform structures.

As mentioned above, another problem with prior designs for salvage units resides in a lack of control to maintain a stable attitude of the unit and of a contained vessel once the vessel is initially lifted away from the bottom of a body of water. Buoyancy must be carefully controlled to avoid an extremely rapid rate of lift of the vessel to the surface, and there is always a danger of the entire system overturning if buoyancies cannot be carefully set and balanced on all sides of the salvage unit and its retained vessel. The present invention overcomes the problems of buoyancy and balance by providing a novel buoyancy compensator means. The buoyancy compensators may be provided in the support frame tanks and in each of the pontoon means 24. FIGS. 10 through 13 illustrate details of a buoyancy compensator 40 in accordance with this invention, and FIG. 6 illustrates placement positions for a plurality of such buoyancy compensators in each pontoon means 24 so that each compartment a through c of a single pontoon means can be controlled as to its positive or negative buoyancy. As shown in FIG. 10, each buoyancy compensator 40 comprises a tubular member which communicates between an outside environment (the sea) and the sealed interior space of a pontoon means (or of a single compartment within a compartmented pontoon or tank). The lowermost end 42 of the buoyancy compensator 40 is adjusted in its vertical level within the compartment space which is to be controlled, and water can be received through the hollow tubular structure of the buoyancy compensator. When air, or other buoyancy gas, is introduced into the same compartment space, water will be displaced outwardly through the buoyancy compensator once the pressure of the air or gas has equalized with the water pressure within the compartment. However, when the water level reaches the lowermost end 42 of the buoyancy compensator, the air or gas will be allowed to escape through the exposed open end 42 and no further water will be displaced from the compartment irrespective of the pressure of the compressed air or gas. Thus, the level at which the lowermost end 42 is extended into the compartment which is to be controlled determines the amount of water which will be left in the compartment when air or gas is introduced into the compartment. This provides for an automatic regulation of buoyancy conditions for each compartment by computing the amount of positive buoyancy which is required and by setting the buoyancy compensator to provide for that amount of positive buoyancy when air or gas is introduced. The buoyancy ofa given compartment or pontoon is adjusted by lifting or lowering the open end 42 of the compensator to a level which corresponds to the desired relationship of water volume and gas volume required for a particular buoyancy. To provide for such a lifting and lowering adjustment of the buoyancy compensator 40, a single tubular member may extend downwardly into a compartment, and means may be provided for lifting and lowering the single tubular member. However, a preferred arrangement is illustrated in FIG. 10 wherein the buoyancy compensator is made up of telescoping tubular elements which can be extended and retracted relative to one another to provide the desired adjustment. As illustrated, a smaller diameter tubular member 44 can be retracted into a larger diameter member 46, and a sealed relationship is provided between the two tubular members. Thus, a lifting or lowering of the element 44 results in an adjustment of position for the open end 42 of element 44. A power operated means 48 may be provided for lifting and lowering the tubular element 44, and FIG. 10 illustrates a hydraulically controlled system for effecting rapid vertical movements of the buoyancy compensator. As illustrated, the system provides for an admisslon of hydraulic fluid under pressure to one side or the other ofa piston 50 fitted within a cylinder 52. Known and conventional control and pumping devices may be provided for pumping hydraulic fluid from surface support vessels into either conduit 54 or 56 to effect a lifting or lowering, respectively, of the tubular duct element 44. Alternatively, it may be desirable to utilize divers to manually adjust the positions of the compensators at underwater levels. Movements of the piston 50 are transmitted by a rod 58 to a bracket 60 affixed to the tubular duct element 44. Another advantage in providing a power system 48 to adjust the buoyancy compensator 40 is that the compensator can be moved very rapidly upwardly with a power system to quickly vent a compartment or tank, if required. For example, if extremely unstable conditions are developing during the lifting of a sunken vessel towards the surface, such as an extreme tendency for the entire salvage unit and its contained vessel to overturn, it is possible to rapidly vent pontoons or tanks on one side (or to vent all tanks simultaneously) by rapidly lifting the buoyancy compensators to vent compressed air from the tanks and to admit water into them. In the illustrated embodiment, the tubular buoyancy compensator 40 extends upwardly through an upper deck of a pontoon 24, and a screen 62 may be provided to prevent the admission of foreign matter into the pontoon. Of course, it will be appreciated that the described buoyancy compensator can be of any desired cross sectional configuration, and the compensator can be used for any tank, pontoon, or compartment for which a buoyancy control is desired.

By using a plurality of buoyancy compensators 40 in combination with separate compartments of the two pontoon means 24, it is possible to carefully control the buoyancy of the salvage unit to match the weight curve of a sunken vessel, and previously calculated positive buoyancies can be set for all of the pontoons and compartments so that the admission of gas into the compartment automatically provides a desired buoyancy effect for the particular job at hand. In practice, the total buoyancy of the two pontoon means 24 is set to substantially match the load weight and distribution of weight of the sunken vessel which is to be lifted. However, this buoyancy is not sufficient to lift the combined weight of both the sunken vessel and the salvage unit itself, and therefore, actual lifting of the vessel does not begin until buoyancy tanks associated with the support frame at 12 are adjusted in their buoyancies. In this sense the buoyancy of the support frame 10 is used to control the sinking and lifting of the entire unit, while the buoyancies of the pontoons is used to match the system to the load which is to be lifted. Thus, the pontoon means 24 can be filled with compressed gas to displace known quantities of liquid as soon as the grasping arms 14 are in position, and there is no danger of a premature lifting or floating of the sunken vessel.

Although each buoyancy compensator 40 may be provided with an open end 42 with no Additional structures or devices, a stabilizer valve means 70 may be utilized for purposes of providing additional features of balance and control. It has been found that the two pontoon means (or whatever numbers are being used in a given structure) on opposite sides ofa salvage unit can be regulated relative to one another to maintain a balance which will assist in keeping the salvage unit and its retained vessel in a preferred upright attitude. Each stabilizer valve means (FIGS. 10, 12 and 13) comprises a valve plate member 72 (a butterfly valve type of known construction is suitable) which is actuated about a pivotal axis 74 by floats 76. The floats 76 are rigidly connected to the valve plate 74 through a bracket structure 78 in such a way that movements of the bracket will directly rock the valve plate 72 about its axis 74 on a pin 80. The valve plate 74 may include a slot through its central portion for receiving a projecting portion of the bracket 78, and the projecting portion of the bracket may be pinned in place relative to the valve plate, so as to be easily disassembled or repaired. The valve plate 72 is set at an angle relative to the open end of the buoyancy compensator, as shown in FIG. 10, so that the stabilizer valve means will have no effect upon the compensator when the floats 76 are riding in a substantially horizontal plane. However, when the floats are tilted, the angle of the plate 72 will be adjusted to provide additional compensation to the buoyancy of the system. The valve plate 72 can be tilted in a clockwise direction about the axis 74 (of FIG. 10) for a sufficient distance to seal the open end 42 of the compensator. The valve plate 72 seals the open end when its peripheral surfaces engage upper and lower valve seats 82 and 84, respectively. With the stabilizer valve means 70 which has been just described, it is possible to relate buoyancy compensators on opposite sides of the salvage unit so that a tilting of the entire unit in one direction about the central longitudinal axis of a retained vessel will automatically provide an adjustment in opposed pontoon means to overcome the unstable condition. FIG. 14 illustrates the relationship which can be provided by the stabilizer valve means 70 when such valve means are situated in buoyancy compensators on opposite sides of the salvage unit. Considering the relationship shown in FIG. 14, the stabilizer valve means 70 of the lefthand pontoon means 24 will seal the open end of the buoyancy compensator 40 if the left pontoon means 24 tilts downwardly relative to the right pontoon means 24 along the line X X. This prevents the escape of any air from the lefthand compartment 24, thereby maintaining its buoyancy. On the other hand, the stabilizer valve means 70 of the righthand pontoon means 24 permits an escape of air from the pontoon during such a tilting movement, and this changes the buoyancy of the righthand pontoon to increase its negative buoyancy. Such a change in buoyancy has the effect of righting the entire system to a more stable condition wherein the two pontoons are related to one another along a substantially horizontal plane. Without a provision for a balancing between opposite sides of the salvage unit, there would be a possibility of a lowermost pontoon losing more and more of its positive buoyancy during the tilting movement just described, and this could lead to an uncontrollable situation which would capsize the entire system.

Although the grasping arm means 14 may be of any suitable shape or configuration, it is possible to provide flexible pad structures on the inner surfaces of the separate arm means 14 so as to provide a frictional engagement of the arm means with the side walls of a vessel being engaged by the opposite rows of arms. FIGS. 15 through 17 illustrate examples of flexible pad structures which may be provided to conform the inner configurations of the arm means to whatever shape of vessel is being encountered. Alternatively, bulkheads can be constructed and installed on the arm means to fit whatever special configuration is encountered in a salvage operation. The flexible pads which are illustrated include a friction pad 92 for actually contacting a vessel. The friction pad 92 is carried and supported by spring means 94 which are interconnected to provide a uniform pressure distribution over the entire contact area of the pad 90. Pivotal connections 96 are provided for attaching the spring means to the arm l4 and to remaining elements of the spring.

FIG. 18 illustrates a piping diagram for compressed air controls for the salvage unit. A bundle of air supply hoses 100 connects the salvage unit to surface support vessels, and the separate hoses communicate with separate parts of the salvage unit through a distribution system made up of pipes 102. The pipes 102 are supported on the upper deck of the support frame 10, and from there a number of the pipes extend, through flexible or telescoping connections 104, to the pontoons 24. In addition, conduits are provided for supplying hydraulic fluid to rams connected between the pontoons and the arms of the unit, and manually operated venting valves 106 are provided for the compartments making up the buoyancy system of the salvage unit.

The operation of the described salvage unit may be in accordance with any known practices for aligning, sinking, and floating submersible devices. As an example of operation, reference is made to FIG. 1 wherein the salvage unit is shown in a floating condition adjacent to the location of a sunken vessel 200. Before salvage operations are started, a survey crew, using standard Navy procedures, determines any intact buoyancy of the sunken vessel 200, and the known weight and load of the vessel is determined from records. The sunken vessel is marked by a mooring system comprising a number of buoys 202 positioned to mark the location of the vessel. The buoys are connected to anchors 204 around the vessel by a first set of cables 206 which extendbetween the anchors 204 and the buoys 202. Preferably, the buoys 202 are connected to the cables 206 so as to be quickly releasable therefrom. One method of aligning the salvage unit with the sunken vessel includes the steps of running slack lines 210 from the buoy positions to the salvage unit floating nearby. This can be accomplished with tugs or other vessels, and then, the salvage unit can be drawn into an aligned position over the sunken vessel by tightening the lines 210. Alternatively, the salvage unit can be towed by an air supply vessel over the mooring system to receive the buoys 202 into a cage by guide runners 208 provided in the salvage unit (see FIGS. 5, 6 and 19). The guide runners 208 function to guide the buoys Into a cage 209 so that the lines 206 and 208 can be connected together. Once the cables and buoys are guided into the cage 209, the buoys 202 are released from the cables 206, and the cables 206 are attached with pelican hooks to a second set of cables 210 which lead up through the salvage unit through guides to another set of buoys 212 positioned on the upper deck of the support frame 10. Once the two sets of cables are connected to one another, there is provided a system of continuous cables from the anchors 204 to winches 214 and buoys positioned on the upper deck of the salvage unit. A book means 211 may be carried on a portion of the pontoon 24 for temporarily receiving an end of a cable 206 while the buoy 202 is being disconnected. The cage 209 may be of any suitable construction to receive and hold a buoy, and preferably the cage 209 is releasably secured to a pontoon so that it can be lifted by cables when it is not needed.

Next, all buoyancy compensators of the pontoon means 24 are adjusted by the power systems 48 to match the buoyancy of the pontoon means 241 with the calculated effective weight for the sunken vessel 200. Flexible pads 90, or bulkheads, are adjusted to fit the particular vessel, and the salvage unit is in condition for sinking. During the sinking procedure, the cables 206 and 210 are maintained taut by winches 214 carried on the salvage unit. Instead F winches, tugs may be used for hauling the cables 207 to maintain them taut. The

next step of the procedure requires the placement of a crew aboard the salvage unit, and the crew floods the end tanks on each of the pontoon means 24. Catwalks may be provided above the deck of the pontoon means so that a crew can find easy access to the pontoons of the floating salvage unit. Initially, the upper deck of the support frame 10 may be feet or more above the surface of the water, but a flooding of the end tanks of the pontoons will bring the upper decks of the pontoons down to the level of the surface of the water. During towing and initial sinking operations, the pontoon means 24 will be locked in their highest positionS, and the arms 14 will be locked against the legs 28 in their most open positions. In order to place the pontoon means 24 in their uppermost positions while, at the same time, malntaining the opposed arms 14 completely open, it is necessary to fully retract the hydraulic rams 26 associated with the linking members between the arms and the pontoon means. In an alternative arrangement, jacking devices associated with the legs of the support frame can adjust the position of the pontoons, and telescoping members can be substituted for the hydraulic rams 26. Once the end compartments of the pontoon means 24 are flooded, the hydraulic rams 26 are extended so as to place the pontoon means 24 at their lowermost positions on the legs 28. Initial placement of the pontoon means 24 at their uppermost positions is done only to strengthen the entire salvage unit while it is being towed to a work site and aligned for sinking.

Once the pontoon means are flooded and moved down to the surface of the water, the crew climbs to the upper deck of the support structure 10 where valves are operated to complete the flooding of all compartments of the pontoon means 24. Then, the tanks of the support frame 10 are flooded as far as sea conditions will permit, and the crew is removed from the salvage unit 10. Final flooding and sinking of the salvage unit 10 is accomplished by venting the tanks of the support frame structure. Venting can be accomplished by the use of compensators 40 in the support frame tanks, such compensators being of the same general construction as discussed above. The compensators may be pr0- vided wlth valves, if desired, for operation from a remote location.

Once the unit is on the bottom, all air in the support frame is vented so that the weight of the entire unit can be used to sink the unit into a grasping position. When the unit is in a proper position for grasping the sunken vessel, the water jets are operated to assist in a placement of the arms under the vessel. Then, air is pumped into the pontoon means 24, causing them to lift on their associated legs 28, thereby causing the arms 14 to move into grasping positions around the sunken vessel. Since the buoyancy compensators for the pontoon means have been set to match the weight of the vessel, but not combined weight of the vessel and the salvage unit, addition of air into the pontoon functions to move the arms 14 into grasping positions without any danger of a premature lifting or floating of the complete system. If necessary, vibrators and the water jets can be used to assist in the movement of the arm means 14 into engagement with the sunken vessel.

Once the sunken vessel is fully retained by the two rows of arms 14, the support frame structure is filled with sufficient air or gas to adjust its buoyancy to lift both the salvage unit and the retained vessel. If sufficlent buoyancy cannot be obtained this way, the buoyancy compensators of the pontoon means can be further adjusted (by remote control, by submersibles, or by divers) to provide additional buoyancy. As the salvage unit begins to lift the vessel, buoyancy on opposite sides of the salvage unit will be adjusted by the stabilizer valving means 70 discussed above if an off-center load is encountered. However, should the salvage unit begin to slip off from the vessel, or if any other complication arises, buoyancy can be quickly relieved by actuating an emergency release switch which causes a simultaneous operation of all compensators to vent air from the pontoon means 24.

Once the salvage unit and vessel have surfaced, air lines or hydraulic lines are connected to the hydraulic rams 26 to force the pontoon means 24 downwardly on their legs 28. Alternatively, jacking means can be used for moving the pontoons relative to the support frame. The pontoon means 24 are moved downwardly for a sufficient distance to lift the freeboard deck, or other structure, of the vessel above the surface of the water. Then, the vessel can be made seaworthy by the use of floatation bags, foam, or any known method or combination of methods for adding buoyancY to a vessel.

Thus, it can be seen that this invention provides for substantially improved features of performance and safety. A sunken vessel can be grasped and lifted to the surface in a controlled operation, and once near the surface, it can be floated and released from the salvage unit, if desired. The salvage unit can continue operations in a given area to lift additional vessels or objects, or it can be floated to another location with a raised vessel retained within its grasp. Of course, the salvage unit can be used in various depths F water even though it is especially useful In deep water operations. The salvage unit which has been described is manufactured and assembled in accordance with known ship building techniques. It may be manufactured from metal plate of suitable thickness, and various parts may be welded, or otherwise secured together, to produce an integral, complete assembly. If desired, the salvage unit can be provided with propulsion devices to make it self-propelling.

Although the invention has been described with reference to a particular embodiment, it will be understood that variations in the described embodiment will become obvious to those skilled in this art. Also, certain modifications or additions can be made to the described structure. All obvious variations and modifications are intended to be included within the scope of this invention.

What is claimed is:

1. A buoyancy compensator means for stabilizing buoyancy of a tank or chamber, comprising a hollow member having an upper end which communicates with an environment surrounding the tank or chamber and a lower end which communicates with an interior space of said tank or chamber, and

valving means carried at said lower end of the hollow member for automatically controlling flow of fluids through the hollow member, said valving means including means responsive to angular deviation of said tank or chamber from a desired orientation in said surrounding environment, said means responsive to angular deviation being operatively associated with said valving means for adjusting the valving means so as to regulate fluid flow through said hollow member.

2. The buoyancy compensator of claim 1 wherein said means responsive to angular deviation comprises means responsive to attitude of a water/air interface within said tank or chamber.

3. The buoyancy compensator of claim 2 wherein said means responsive to attitude of a water/air interface comprises a pair of float means carried in spaced relationship to each other by a bracket assembly.

4. The buoyancy compensator of claim 3 wherein said valving means includes a plate member which can be rocked about a fixed pivot axis relative to an internal cross-section of said hollow member so as to regulate fluid flow through the hollow member.

5. The buoyancy compensator of claim 4 wherein said plate member is connected to said bracket assembly so as to be rocked by changes in attitude of the float means carried by the bracket assembly.

6. The buoyancy compensator of claim 1 and including means for adjusting the vertical distance at which said lower end of said hollow member can extend into said tank or chamber so as to establish an interface between two separate fluids, having two different densities, contained within said tank or chamber.

7. The buoyancy compensator of claim 6 wherein said hollow member comprises a tubular member.

8. The buoyancy compensator of claim 7 wherein said tubular member is made up of at least two telescoping sections.

9. The buoyancy compensator of claim 6 wherein said means for adjusting vertical distance of said hollow member comprises power operated means operatively connected to said lower end of the hollow member for extending and retracting the hollow member. 

1. A buoyancy compensator means for stabilizing buoyancy of a tank or chamber, comprising a hollow member having an upper end which communicates with an environment surrounding the tank or chamber and a lower end which communicates with an interior space of said tank or chamber, and valving means carried at said lower end of the hollow member for automatically controlling flow of fluids through the hollow member, said valving means including means responsive to angular deviation of said tank or chamber from a desired orientation in said surrounding environment, said means responsive to angular deviation being operatively associated with said valving means for adjusting the valving means so as to regulate fluid flow through said hollow member.
 2. The buoyancy compensator of claim 1 wherein said means responsive to angular deviation comprises means responsive to attitude of a water/air interface within said tank or chamber.
 3. The buoyancy compensator of claim 2 wherein said means responsive to attitude of a water/air interface comprises a pair of float means carried in spaced relationship to each other by a bracket assembly.
 4. The buoyancy compensator of claim 3 wherein said valving means includes a plate member which can be rocked about a fixed pivot axis relative to an internal cross-section of said hollow member so as to regulate fluid flow through the hollow member.
 5. The buoyancy compensator of claim 4 wherein said plate member is connected to said bracket assembly so as to be rocked by changes in attitude of the float means Carried by the bracket assembly.
 6. The buoyancy compensator of claim 1 and including means for adjusting the vertical distance at which said lower end of said hollow member can extend into said tank or chamber so as to establish an interface between two separate fluids, having two different densities, contained within said tank or chamber.
 7. The buoyancy compensator of claim 6 wherein said hollow member comprises a tubular member.
 8. The buoyancy compensator of claim 7 wherein said tubular member is made up of at least two telescoping sections.
 9. The buoyancy compensator of claim 6 wherein said means for adjusting vertical distance of said hollow member comprises power operated means operatively connected to said lower end of the hollow member for extending and retracting the hollow member. 